Q&A: A Forum for Green Building Experts and Beginners

Q & A Instructions

[Click map to enlarge]

The GBAGreenBuildingAdvisor.com web site has a wealth of articles on a wide variety of construction topics. Before posting your question, you may want to check out the articles on this page: How To Do Everything. You just might discover an article there that provides the information you seek.

Please register for a free account or sign in to ask and answer green building questions.

If you want to post a question, the usual rules of courtesy apply:
1. Be nice.
2. If you can't be nice, be polite.
3. If you can't be nice or polite — well, please be brief.

To attach a photo or illustration: Under the box labeled “More explanation,” look for the words “File attachments.” Click that, and you should be able to attach a photo.

Thanks for joining the conversation!


4 Answers

Is it OK to insulate under basement floor slab with rigid foam if there is rigid foam on exterior of basement walls?

The slab will be isolated with foam but the foundation will not have a completely closed envelope since the basement walls have rigid foam on the exterior. How much of a concern is the thermal bridge at the footing? This is in Columbus, OH.

In Energy efficiency and durability | Asked By Jason Hackworth | May 19 10
6 Answers

Attic Truss, Cellulose & Venting

We are designing a small home (1100 sf footprint) hoping to use attic trusses and two sets of shed dormers to create a small office and art studio space upstairs. I prefer fitting these spaces into the roof, if possible, instead of adding a full 2nd story. The walls are 1' thick Faswall. I live in North Idaho, and the winter air is often quite humid. I prefer cellulose over spray foams for environmental reasons, but would still like to have R50+ in the roof.

In Green building techniques | Asked By Ron Bedford | May 18 10
56 Answers

What constitutes green building?

A good and often asked question.
I have read more definitions of what "green" means than I can remember.
I often hear references to "shades of green".

If one acknowledges the severity of the problems we collectively face then one must acknowledge the need to difine a holistic solution to these problems (no matter how stringent the requirements of the definition).
It seems to me that the adjective "green" does NOT currently meet this requirement.

In General questions | Asked By Lucas Durand | May 9 10
17 Answers

Is there a way to calculate depressurization values from blower door test results?

OK, this question is for you building scientists and certified blower door testers . . .

Given a theoretical house size, volume, and airtightness result, is there a way to convert a flow rating into a pressure rating?

Example: Two story house, 30' x 30' footprint, 20' wall height (this would include sealed crawlspace and floor joist area)

* Surface Area = 3,300 sq. ft. (Walls and Ceiling)

* Volume = 18,000 cu. ft.

* Blower Door Test Result = 0.77ACH50

What is the effective depressurization if the bathroom and kitchen exhaust fans are pumping out 150 CFM?

In Energy efficiency and durability | Asked By Daniel Ernst | May 12 10
5 Answers

How to make galvanized metal roofing look distressed

We would like to re-use some old metal roofing as house siding and for small horse barns. How do we remove the color and make it look distressed, like old western tin roofing/siding? Thank You.

In General questions | Asked By Barbara Christ | May 18 10
2 Answers

If you use foam insulation over wall sheathing, do you still need the building wrap?

If you house is continuously sheathed and then wrapped with 1" of foam insulation, with the joints sealed, do you still need the building wrap over the OSB?

In Green building techniques | Asked By shaun majors | May 17 10
6 Answers

Will a wall furnace meet the energy code if heating many rooms?

A mechanical contractor suggests heating a 1,000 sq. ft. 3-bedroom condo with a wall furnace installed in the main room. The heat will be transferred to other rooms by the installation of through-the-wall fans. There will be one thermostat on the furnace. Will this meet any kind of energy code? This is in Massachusetts.

In Energy efficiency and durability | Asked By joe | Mar 13 10
10 Answers

Polyisocyanurate foam retrofit and rainscreen

I have a question about a job I am starting in Amherst, MA. and I would like to hear others chime in about it. This is a whole house exterior renovation (built in 1982) The owner's want to insulate and install new windows and siding.

Existing wall from inside to outside: 1/2" drywall, 1" polyiso., 2x6's 16" oc w/ fiberglass batt insul, 1/2" asphalt coated 'Beaverboard' sheathing(OSB on corners), Tyvek ( which has deterriorated) and 1x cedar vertical siding.

In Energy efficiency and durability | Asked By John Hondrogen | May 10 10
12 Answers

Where is the best place to put a carbon monoxide detector in a home?

I was told that they should be placed really low because carbon monoxide is heavier than air.

In General questions | Asked By ronald miller | May 9 10
4 Answers

Is this wall system adequate for Zone 6a — maritime climate?

I would like to build a garage with 2"x6"x 10' studs. From exterior to interior: 3/8" ply siding, 3/8" gap, Tyvek wrap, 1" EPS board, 2"x6" studs, 4" EPS fitted between studs, 6-mil vapor barrier (called for by code), then drywall.

In Energy efficiency and durability | Asked By James | May 13 10
Register for a free account and join the conversation


Get a free account and join the conversation!
Become a GBA PRO!